Increased sorbency of fibrous nonwoven webs has been desired, particularly when the webs are for use in such products as disposable diapers, incontinent devices, surgical dressings, and wipers.
U.S. Pat. No. 4,100,324 (Anderson et al.) discloses a nonwoven fabric-like material which consists essentially of an air-formed matrix of thermoplastic polymer microfibers having an average fiber diameter of less than about 10 microns, and a multiplicity of individualized wood pulp fibers disposed throughout the matrix of microfibers and engaging at least some of the microfibers to space the microfibers apart from each other. The wood pulp fibers are interconnected by and held captive within the matrix of microfibers by mechanical entanglement of the microfibers with the wood pulp fibers.
U.S. Pat. No. 4,429,001 (Kolpin et al.) discloses sorbent sheet products which comprise a coherent web of entangled blown fibers and an array of solid high-sorbency liquid-sorbent polymeric particles dispersed within the web. The blown fibers are prepared by extruding liquid fiber-forming material into a high-velocity gaseous stream where the extruded material is attenuated and drawn fibers. The sorbent particles are introduced into the stream of fibers and the mixture of fibers and particles is collected as an entangled coherent mass.
U.S. Pat. No. 4,650,479 (Insley) discloses a sorbent sheet product, particularly useful for disposable diapers, incontinent devices, and sanitary napkins, which comprises a coherent fibrous web that includes entangled blown polymeric fibers and high sorbency, liquid sorbent fibers intermingled with the blown polymeric fibers. The product may also contain liquid transport fibers.
European Patent Publication No. 0 156 649 (Minnesota Mining and Manufacturing Company) discloses a sorbent sheet product which comprises a coherent fibrous web that includes entangled blown fibers and liquid transport fibers intermingled with the blown fibers and an array of solid high sorbency liquid-sorbent polymeric particles uniformly dispersed and physically held within the web. The particles swell upon sorption of liquid, and the transport fibers cause increased and more rapid sorption of liquid by conducting the liquid from external portions of the web to internal portions of the web.
Increased efficiency of fibrous nonwoven webs used as filtration media, such as in face masks, cartridge filters, and other air filters, and liquid-liquid filters has been desired.
U.S. Pat. No. 3,073,735 (Till et al.) discloses a method for producing filters wherein fibers from a plurality of fiber-forming means are suspended in a gas stream and deposited on a collecting surface. The fibers of each fiber-forming means differ in physical characteristics from those of the other means, e.g., one of the fibers may be preformed, such as staple textile fibers and the other fiber may be produced in situ by feeding a plastic fiber-forming composition from a reservoir to a spraying unit which comprises a spraying tube positioned in the center of a nozzle through which air is forced at a high velocity. The fibers are deposited on the collecting device in such intermingled relationship that there is a gradual gradation in fiber property along one dimension of the filter.
U.S. Pat. No. 3,316,904 (Wall et al.) discloses a filtering web for face masks which comprises a dimensionally stable, expanded lofty web of a blend of discontinuous, relatively coarse thermoplastic fibers and relatively fine thermostable fibers adhered to one another in a manner providing a lofty reticulated web while yet remaining dimensionally stable and resistant to matting and the web requires no inert filler fibers or the like in its formation.
U.S. Pat. No. 3,971,373 (Braun) discloses a self-supporting durable flexible conformable low-pressure-drop porous sheet product that contains a uniform three-dimensional arrangement of discrete solid particles. The sheet product comprises, in addition to the particles, a web of melt-blown microfibers in which the particles are uniformly dispersed. The particles are physically held in the web, even though there is only point contact between the microfibers and the particles, whereby the full surface of the particles is available for interaction with a medium to which the sheet product is exposed.
U.S. Pat. No. 4,011,067 (Carey, Jr.) discloses a filter medium which can remove a high percentage of fine particles from a gas stream and which comprises a base porous web, one or more lightweight non-self-supporting layers of microfibers collected and carried on the base porous web, and a top porous web.
Increased thermal insulating properties in fibrous nonwoven webs have been desired, particularly when the webs are for use in such products as outerwear, such as ski jackets, sleeping bags, and bedding, such as comforters.
U.S. Pat. No. 3,892,909 (Miller) discloses fibrous bodies simulating natural bird down which include larger circular bodies, or figures of revolution, and smaller feather bodies, the feathery bodies tending to fill the voids formed by the larger circular bodies. The fibrous bodies are preferably formed from synthetic fiber tow.
U.S. Pat. No. 4,118,531 (Hauser) discloses a thermal insulating material which is a web of blended microfibers and crimped bulking fibers which are randomly and thoroughly intermixed and intertangled with the microfibers. The crimped bulking fibers are generally introduced into a stream of blown microfibers prior to their collection. This web combines high thermal resistance per unit of thickness and moderate weight.
U.S. Pat. No. 4,144,294 (Werthaiser et al.) discloses a substitute for natural down comprising sheets of garneted polyester which are separated into a plurality of small pieces, each of which pieces is generally formed into a rounded body. Each of the rounded bodies includes a plurality of randomly oriented polyester fibers therein, and each of the rounded bodies provides a substantial resiliency to permanent deformation after the application of force to them.
U.S. Pat. No. 4,588,635 (Donovan) describes synthetic down thermal insulating materials which are batts of plied card-laps of a blend of 80 to 95 weight percent of spun and drawn, crimped, staple, synthetic polymeric microfibers having a diameter of from 3 to 12 microns and 5 to 20 weight percent of synthetic polymeric staple macrofibers having a diameter of from more than 12, up to 50 microns. Donovan describes this fiber blend as comparing favorably to down or mixtures of down with feathers as an insulator in that it will provide an equally efficient thermal barrier, be of equivalent density, possess similar compression properties, have improved wetting and drying characteristics, and have superior loft retention while wet. The fibers form these batts by physical entanglement of the fibers achieved during carding. An expanded discussion of these same materials can be found in Dent, Robin W. et al., DEVELOPMENT OF SYNTHETIC DOWN ALTERNATIVES, Technical Report Natick/TR-86/021L - Final Report, Phase 1.